WHICH PORTS
WHERE LOCAL REMOTE PROGRAMMED
MLTID NAME CREATED PORT MEMBERS PORT MEMBERS IN DATA PATH
----------------------------------------------------------------------------------------------------
1 MLT-1 LOCAL 1/4 LOCAL

WHICH PORTS
WHERE LOCAL REMOTE PROGRAMMED
MLTID NAME CREATED PORT MEMBERS PORT MEMBERS IN DATA PATH
----------------------------------------------------------------------------------------------------
1 MLT-1 LOCAL 1/4 LOCAL

When you add a VLAN to a dynamic MLT, only the active ports of the MLT are added as port members of the VLAN. Ports configured with the same aggregation key, but not active, are not added to the VLAN. If these inactive ports become active later, the system does not automatically add them to the VLAN port member list.You must add all inactive ports to the VLAN. If you do not add the inactive ports to the VLAN, when they become active later, hashing can result in choosing a newly active port for traffic forwarding. Because the port is not a port member of the VLAN, traffic will be dropped. When you add the VLAN to the MLT, also add the inactive aggregation ports to the VLAN. You may need to disable LACP on the inactive ports before you can add them to the VLAN. Because the ports are inactive, disabling LACP does not cause a traffic interruption.

So in case of dynamic MLT the prefered way is to add vlan on individual ports. And while doing this LACP cannot be enabled on those ports. That's why I recommended disabling lacp, add ports to the vlan and enable lacp again. From the question it is not clear if all ports are active members or not.

Hi all, I have a similar task, 2x VSP7200 stacked switches are connected with 4x10G ports in a LAG to a Cisco VHS cluster, at Cisco end it is a single PortChannel. Now we need to add new VLANs to this LAG and for that we have to disable and re-enable LACP on both VSP switches. Is this service-affecting? Obviously it will happen out of hours, but if it is affecting then the change window and amount of regression testing on the apps side, and overall perceived risk will be much larger.
Thanks!